Electromagnetic spectrum

Question 1

what are 3 factors about electromagnetic waves that are always true

Answer 1

1. are all transverse waves
2. travel at the same speed in a vacuum
3. transfer energy

Question 2

what are the 7 parts of the electromagnetic spectrum from longest to shortest wavelength

Answer 2

radiowaves
microwaves
infrared
visible light
ultra-violet rays
xrays
gamma-rays

Question 3

what is the speed of an electromagnetic wave

Answer 3

3 * 10 to the power of eight

Question 4

what 2 things are an electromagnetic wave made up of

Answer 4

magnetic wild and electric field

Question 5

what are 4 behaviours of electromagnetic waves

Answer 5

reflected on a surface
refracted when they move from one material to another
transmitted when they pass through a material
absorbed by different materials

Question 6

why can’t xrays and gamma rays reach the surface of the earth

Answer 6

they are absorbed by the atmosphere

Question 7

how are microwaves used for communication

Answer 7

a microwave signal is sent from one transmitting aerial into the atmosphere where the ionosphere will transmit it to a communication satellite in space which will transmit it back through the ionosphere to a receiving aerial

Question 8

how are radio waves used for communication

Answer 8

a transmitting aerial sends the signal towards the atmosphere where it is refracted by the ionosphere and sent back down towards the earth 2 A receiving aerial

Question 9

how are temperature and EM radiation linked together

Answer 9

any object above absolute zero will emit electromagnetic radiation

Question 10

what 3 rules that affect temperature

Answer 10

1. a body at a constant temperature absorbs and emits the same amount of radiation
2. an object will increase in temperature if it absorbs more radiation that emits
3. an object will decrease in temperature if it emits more radiation than it absorbs

Question 11

the higher the temperature the _________ the wavelength

Answer 11

shorter

Question 12

what colour will emit absorb the most EM radiation

Answer 12

an object that is shiny white

Question 13

what is the name of the practical cube used to show how different coloured surfaces absorb or emit radiation

Answer 13

Leslie cube

Question 14

give 2 uses for radiowaves

Answer 14

• broadcasting radio and TV programs
• communicating with ships, satellites and aeroplanes

Question 15

give 2 uses for microwaves

Answer 15

• in mobile phones, and to communicate by satellite transmission
• for cooking

Question 16

give 5 uses of infrared

Answer 16

• cooking (grills and toasters)
• used for thermal images
• short-range communication
• remote controls for TVs
• to send information along fibre optic cables
• in security systems such as burglar alarms to detect people moving

Question 17

give 2 uses of visible light

Answer 17

• allow us to see
• photography

Question 18

what are 4 uses of ultraviolet?

Answer 18

to detect security markers made using special pens
- fluorescent lamps
- to detect forged banknotes
- to disinfect water

Question 19

what are 2 uses of xrays

Answer 19

• medical xrays to see inside the body
• airport security scanners

Question 20

what are 3 uses of gamma rays

Answer 20

to sterilise food and medical equipment
in scanners to detect cancer
to treat cancer

Question 21

what is the danger of microwaves

Answer 21

microwaves heat water, so they can heat the water inside our bodies, which can damage or kill them

Question 22

what is the danger of infrared

Answer 22

too much infrared can cause skin burns

Question 23

what is the danger of ultraviolet

Answer 23

UV in sunlight can damage skin cells and cause sunburns, overexposure to UV can cause skin cancer. it can also damage the eyes

Question 24

what is the danger from X-rays and gamma rays

Answer 24

can cause mutation in the DNA, which can kill the cells or cause cancer